Polymer composition for electrical part material

ABSTRACT

A polymer composition for electrical part material comprising, (I) a polymer blend which comprises (A) at least one polymer selected from specific types of polyether imides and polyesters, and (B) at least one polymer selected from specific types of polyphenylene ethers, polyolefins, and polycarbonates, and (II) a copolymer of maleic anhydride and vinyl type compound or (II&#39;) an epoxy-modified styrene-type copolymer. The composition has excellent compatibility, heat resistance, mechanical characteristics, platability, moldability, and electric characteristics. It is an ideal material for use as an electrical part material due to its low dielectric constant and low dielectric dissipation factor at high frequency.

This is a Division of application Ser. No. 08/266,382 filed on Jun. 27,1994, pending.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a polymer composition for electricalpart material.

2. Description of Background Art

Along with development of high frequency-related technologies, there isa tendency that a wider frequency band is used for equipments for signaltransmittance. Some equipments are designed to receive or transmitsignals with a frequency in the range of several hundred megaheltz (MHz)to several hundred gigaheltz (GHz). Materials used in electricalequipments using high frequency, specifically, materials used fordevices or parts, such as packages, wiring circuit board substrates,sockets, and connecters, as well as materials for connecting thesedevices or parts, must have excellent electrical characteristics, suchas a low dielectric constant and a low dielectric dissipation factor.The electric loss also must be small.

Beside the excellent electrical characteristics, superior moldabilityand metal platability are also required for electrical insulationmaterials, particularly those using high frequency.

Polyether imide, polyester, polyimide, and the like are popularengineering plastics due to their high heat resistance, excellentelectrical insulation, and superior mechanical properties. These arealso widely used as electrical insulating materials such as ICsubstrates and printed wiring board substrates because of theirexcellent heat resistance and electrical insulation.

These condensed aromatic-type heat-resistant polymers, however, exhibitonly limited performances as insulating materials for high-density,multi-layered, integrated circuits or high-speed, high-frequencycircuits due to their comparatively high dielectric constant anddielectric dissipation factor.

On the other hand, polyphenylene ether, polyolefin, polycarbonate,aromatic polyvinyl compounds, and the like have a low dielectricconstant, dielectric dissipation factor, and other excellent electricalproperties, although these are inferior in the mechanical properties,and heat resistance.

A number of studies are being undertaken on the design of polymer blendsfor the purpose of obtaining materials exhibiting two or more excellentcharacteristics possessed by these different-types of polymers.

A serious problem in these polymer blends is incompatibility of thecomponent polymers. A number of polymers are incompatible each other,which is a cause of inferiority of various characteristics, especiallymechanical properties.

For increasing the compatibility between polyether imide andpolyphenylene ether, each having excellent characteristics as mentionedabove, Japanese Patent Laid-open (kokai) No. 32880/1993 proposesincorporation of an epoxy-modified aromatic vinyl resin to the polymerblends as a compatibilizer.

Although epoxy-modified aromatic vinyl resin used in the Japanese PatentLaid-open (kokai) No. 32880/1993 as the compatibilizer can promoteinteractions among polymers, this resin is inferior in the heatresistance by itself. If used in a large amount in a polymer blendcomprising polyether imide and polyphenylene ether, it may impairexcellent heat resistance inherently possessed by the former polymers.

In addition, because this compatibilizer has a lower crystalline orglass transition point than that of polyether imide and polyphenyleneether, the three-component polymer blend may result in unhomogeneousmolded articles with a surface layer consisting of the compatibilizer,if it is used in a large amount.

This unhomogeneous property may a cause of decreased heat resistance,electrical characteristics, and mechanical characteristics, especiallywhen the molded articles are prepared by repeated melting operations.

In the case of electrical insulation materials used for electricalparts, e.g., IC board substrates or printed circuit board substrates,etc., high thermal conductivity is desired for efficiently dissipatingheat generated during the time when these are used, in addition toexcellent characteristics such as heat resistance, mechanicalcharacteristics, electrical insulation properties, dielectricproperties, and moldability.

However, because polymers generally have only small thermalconductivity, improvements in the conductivity is difficult ifcomponents for the blend is limited to polymers. Thus, this prior artcomposition remains insufficient with respect to thermal conductivity.

An object of the present invention is therefore to solve the problem ofthe poor compatibility among polymers without causing theabove-mentioned problem of unhomogeneity in the molded articles, and toprovide a polymer composition for use as an electronic material suitablefor use at a high frequency range, which exhibits not only excellentelectrical insulation, dielectric properties, heat resistance,mechanical characteristics, and moldability, but also superb heatcharacteristics such as thermal conductivity, and yet capable ofexcellently molded even if the same may be repeatedly molded.

The present inventors have undertaken extensive studies in order toachieve this object, and found that a combination, at a specificproportion, of (I) a polymer blend which comprises (A) at least onepolymer selected from specific types of polyether imides and polyesters,and (B) at least one polymer selected from specific types ofpolyphenylene ethers, polyolefins, and polycarbonates, and (II) acopolymer of maleic anhydride and vinyl type compound, and, optionally,(III) fillers and the like, can provide a composition (hereinafterreferred to as the first composition) with excellent compatibility, heatresistance, mechanical characteristics, metal platability, andmoldability, while exhibiting superior electrical characteristics, suchas reflecting and passing properties, i.e., a small return loss and asmall insertion loss.

The inventors have further found that (I) said polymer blend, ifcombined with a very small amount (0.1-1.0 parts by weight for 100 partsby weight) of (II') an epoxy-modified styrene-type copolymer, especiallya grafted epoxy-modified styrene copolymer, and, optionally, (III)fillers and the like, can provide a composition (hereinafter referred toas the second composition) with the same excellent characteristics asthe first composition. This finding was surprising in that there is nodecrease in the compatibility even though the amount of theepoxy-modified styrene-type copolymer is very small, and also there isno problem of unhomogeneity even though the composition is repeatedlymolded.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a polymercomposition for electrical part material which comprises,

(I) a polymer blend which comprises,

(A) at least one polymer selected from the group consisting of,

(a) a polyether imide represented by the following formula (1), ##STR1##wherein n indicates an integer of 1-10,000, R₁ represents a group##STR2## and R₂ represents a group ##STR3## and (b) polyestersrepresented by the following formulas (2-1) to (2-11), ##STR4## whereinn indicates an integer of 1-10,000, ##STR5## wherein n indicates aninteger of 1-10,000, ##STR6## wherein n indicates an integer of1-10,000, ##STR7## wherein n indicates an integer of 1-10,000, ##STR8##wherein n indicates an integer of 1-10,000, ##STR9## wherein n indicatesan integer of 1-10,000, ##STR10## wherein x and y are integerssatisfying an equation x+y=2 to 10,000, ##STR11## wherein x and y areintegers satisfying an equation x+y=2 to 10,000, ##STR12## wherein x andy are integers satisfying an equation x+y=2 to 10,000, ##STR13## whereinn indicates an integer of 1-10,000, or ##STR14## wherein x and y areintegers satisfying an equation x+y=2 to 10,000, and (B) at least onepolymer selected from the group consisting of,

(c) polyphenylene ethers represented by the following formula (3),##STR15## wherein n indicates an integer of 1-1000, Y₁, Y₂, Y₃, and Y₄individually represent hydrogen or methyl group,

(d) polyolefins represented by the following formula ##STR16## wherein Ris an alkyl group having 1-10 carbon atoms, an aromatic group having6-10 carbon atoms, or a hydrogen, an n is an integer of 1-100,000, and

(e) polycarbonates represented by the following formulas (5-1) to (5-7),##STR17## wherein n indicates an integer of 1-10,000, ##STR18## whereinn indicates an integer of 1-10,000, ##STR19## wherein n indicates aninteger of 1-10,000, ##STR20## wherein n indicates an integer of1-10,000, ##STR21## wherein n indicates an integer of 1-10,000,##STR22## wherein n indicates an integer of 1-10,000, or ##STR23##wherein n indicates an integer of 1-10,000; and (II) a copolymer ofmaleic anhydride compound and divinyl-type compound,

wherein the amount of component (II) is 0.1 to 50 parts by weight for100 parts by weight of said polymer blend (I).

Another object of the present invention is to provide a polymercomposition for electrical part material which comprises,

(I) the polymer blend defined above, and

(II') an epoxy-modified styrene-type copolymer, wherein the amount ofcomponent (II') is 0.1 to 1.0 part by weight for 100 parts by weight ofthe total amount of said polymer blend (I).

Still another object of the present invention is to provide a polymercomposition for electrical part material which comprises,

(I) the polymer blend defined above, and

(II) a copolymer of maleic anhydride compound and divinyl-type compoundand (II') an epoxy-modified styrene-type copolymer,

wherein the amount of components (II) and (II') is 0.1 to 50 parts byweight for 100 parts by weight of the total amount of said polymer blend(I).

Other and further objects, features and advantages of the presentinvention will appear more fully from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1(A) is a drawing showing a test leaf used for the determination ofreturn loss and insertion loss in the polymer composition of the presentinvention, and FIG. 1(B) shows a holder for an electromagnetic shielder.

FIG. 2 is a drawing illustrating the overall construction of anelectrical characteristic evaluation apparatus used for thedetermination of return loss and insertion loss, wherein numeral 1indicates synthesized sweeper, 2 connector, 3 DUT (an object to bemeasured), 4 detector, 5 bridge circuit, and 6 scaranet work analyzer.

FIG. 3 is a block diagram of the circuit in the electricalcharacteristic evaluation apparatus of FIG. 2.

FIG. 4 is a portion of the circuit for measuring return loss and takenfrom the circuit of FIG. 3.

FIG. 5 is a portion of the circuit for measuring insertion loss andtaken from the circuit of FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS

Among the polyether imides, polyesters, polyphenylene ethers,polyolefins, and polycarbonates, the following compounds are especiallypreferred for use in the present invention, in view of the availability,costs, characteristics of the resulting composition, and the productionprocess.

<Polyether Imides> ##STR24## wherein n indicates an integer of 1-10,000.<Polyesters> ##STR25## wherein x and y are integers satisfying anequation x+y =2 to 10,000, ##STR26## wherein x and y are integerssatisfying an equation x+y =2 to 10,000, ##STR27## wherein x and y areintegers satisfying an equation x+y=2 to 10,000, ##STR28## wherein nindicates an integer of 1-10,000, or ##STR29## wherein x and y areintegers satisfying an equation x+y =2 to 10,000, and <PolyphenyleneEthers> ##STR30##

Polyphenylene ethers without modification or with a least degree ofmodification are preferred in view of high heat resistance. However,from the aspect of moldability and the like, those modified to a certainextent are preferred. Thus, the types of the polyphenylene ethers aresuitably selected depending on the purpose of use.

<Polyolefins>

Polyethylene, polypropylene, poly-4-methyl-1-pentene, poly-1-butene,polybutadiene, polystyrene, syndiotactic polystyrene,poly-p-methylstyrene, poly-p-fluorostyrene, poly-p-chlorostyrene,poly-p-bromostyrene, and the like.

<Polycarbonates> ##STR31## wherein n indicates an integer of 1-10,000.##STR32## wherein n indicates an integer of 1-10,000.

A preferable ratio by weight of polymers (A) and (B) in the polymerblend (I) in the composition of the present invention is (A):(B)=10:90to 90:10, and more preferably 20:80 to 80:20. If the proportion ofpolymers (A) is small, the composition has decreased mechanicalstrength, heat resistance, and the like, but it has improved electricalcharacteristics such as a small dielectric constant and a smalldielectric dissipation factor. If the amount of polymers (A) is large,the composition has increased mechanical strength, heat resistance, andthe like, but the electrical characteristics are decreased, with higherdielectric constant and dielectric dissipation factor.

Because the characteristics of polymers (A) and polymers (B) arecontradictory each other in this manner, it is possible to obtain adesired dielectric constant, mechanical strength, and the like bysuitably adjusting the ratio of these two types of polymers within theabove-defined range.

Examples of preferred combinations of polymers (A) and (B) summarized inthe following table.

    ______________________________________                                        Polymer (A)          Polymer (B)                                              ______________________________________                                        Polyether imides + Polyester                                                                       Polyphenylene ether                                      Polyether imide      Polyphenylene ether                                      Polyether imide      Polycarbonate                                            Polyester            Polyphenylene ether                                      Polyester            Polycarbonate                                            ______________________________________                                    

In the first composition of the present invention, the copolymer ofmaleic anhydride and vinyl type compound (II) is incorporated as acompatibilizer in an amount of 0.1-50 parts by weight, preferably 1-10parts by weight, for 100 parts by weight of said polymer blend (I).

Copolymers of maleic anhydride and vinyl type compound which arepreferable for use in the present invention in view of performances,costs, and the like include maleic anhydride-styrene copolymer, maleicanhydride-ethylene copolymer, maleic anhydride-propylene copolymer,maleic anhydride-methyl methacrylate copolymer, maleicanhydride-acrylonitrile copolymer, maleic anhydride-α-methylstyrenecopolymer, maleic anhydride-p-methylstyrene copolymer, maleicanhydride-N-phenylmaleimide copolymer, and the like. Of these, maleicanhydride-styrene copolymer is particularly preferred. Either one ofthese may be used individually or two or more of them may be used incombination. These copolymers of maleic anhydride and vinyl typecompound may be alternate copolymers, block copolymers, or randomcopolymers.

If the amount of the copolymer of maleic anhydride and vinyl typecompound (II) is too small, sufficient compatibility cannot be achieved,resulting in the polymer composition with decreased mechanical strength.The compatibility among polymers is decreased also in the case wherethis amount of the copolymer of maleic anhydride and vinyl type compound(II) is too large. In this case, the heat stability of the resultingcomposition is also impaired. Thus, it is essential that the proportionof the copolymer of maleic anhydride and vinyl type compound (II) to thepolymer blend (I) be within the range defined above.

In the second composition of the present invention, the epoxy-modifiedstyrene-type copolymer (II') is incorporated as a compatibilizer in anamount of 0.1-1.0 parts by weight, preferably 0.2-0.8 parts by weight,for 100 parts by weight of said polymer blend (I).

Epoxy-modified styrene-type copolymers which are preferable for use inthe present invention in view of performances, costs, and the likeinclude epoxy-modified styrene-styrene copolymer, epoxy-modifiedstyrene-methyl methacrylate copolymer, and the like. Either one of thesemay be used individually or two or more of them may be used together.

These epoxy-modified styrene-type copolymers may be graft copolymers,alternate copolymers, block copolymers, or random copolymers. Graftepoxy-modified styrene-type copolymers are particularly preferred,because graft copolymers enhance mutual actions among molecules, bywhich a three dimensional network structure between polymers (A) andpolymers (B) is formed. Such a network structure not only preventsitself from being located as a layer on the surface of the moldedarticles, but also effectively increases the durability of the moldedarticles and makes it possible to be repeatedly molded.

If the amount of the epoxy-modified styrene-type copolymer (II') issmaller than 0.1 part by weight for 100 parts by weight of the polymerblend (I), the compatibility among the polymers is insufficient,resulting in poor mechanical strength of the resulting composition. Ifthis amount is 1.0 parts by weight or larger, on the other hand, thereis a problem of incapability of repeated molding of the polymercomposition.

Compatibilizers (II) and (II') may be used in combination. In thisinstance, the amount of (II) plus (II') is 0.1-50 parts by weight for100 parts by weight of the polymer blend (I). Taking the homogeneity ofthe resulting composition into consideration, the amount ofcompatibilizer (II') is preferably 0.1-1.0 part by weight.

A filler (III) may be optionally added to the polymer composition of thepresent invention. Incorporation of fillers can improve mechanicalcharacteristics, heat properties, electrical characteristics, metalplatability, and the like. Specific examples of fillers which can beused include inorganic fillers, such as glass, aluminum oxide, magnesiumoxide, beryllium oxide, titanium oxide, aluminum nitride, siliconnitride, boron nitride, titanium nitride, silicon carbide, potassiumtitanate, aluminum borate, and calcium carbonate. Of these preferred aresilicon carbide, silicon nitride, aluminum oxide, potassium titanate,glass, beryllium oxide, aluminum nitride, aluminum borate, and calciumcarbonate. These fillers are used in an amount of 0.001 to 10 parts byweight, preferably 0.01 to 5 parts by weight, for 100 parts by weight ofpolymer blend (I) and compatibilizers (II) and/or (II').

Any types of fillers, such as whisker-type, fiber-type, spherical-type,and powder-type, can be used in the present invention. Whisker-type andmono-filament fiber-type fillers are particularly preferred in order topromote mechanical, heat, and other characteristics of the polymercomposition. Silicon carbide, silicon nitride, aluminum oxide, potassiumtitanate, aluminum borate, aluminum nitride, or calcium carbonatewhisker-type or mono-filament fillers are especially preferred.

In the case where whisker-type fillers are used, the length of whiskeris about 5-50 μm, preferably about 20-40 μm, with a diameter of about0.1-1.8 μm, preferably about 0.3-0.9 μm. If the length is too short andthe diameter is too small, the performances exhibited by the whisker areinsufficient; if the length is too long and the diameter is too large,the whisker shape may be destroyed when the filler is blended.

In the case where monofilament-type fillers are used, the length of themonofilament is about 2000-4000 μm, preferably about 2000-2600 μm, witha diameter of about 4-15 μm, preferably about 8-11 μm. If the length istoo short and the diameter is too small, the mechanical strength of theresulting composition is impaired; if the length is too long and thediameter is too large, the other characteristics are inadequate.

Fillers treated with a silane coupling agent, such asγ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, orN-phenyl-γ-aminopropyltrimethoxysilane, may be also used.

Beside the above-described components (I), (II) and/or (II'), and (III),other components, such as heat stabilizers, flame retardants, coloringagents, and reinforcing agents, may be added to the polymer compositionof the present invention.

The melt-blending method, the solution-blending method, or the like canbe employed for preparing the polymer composition from above-describedcomponents.

The solution-blending method can be implemented at a low temperaturewithout using complicated equipments, while it has disadvantages, suchas requirement of a large amount of solvents, and complicated processsteps. The melt-blending method, on the other hand, is superior becauseof the simple process. Because mass production requiring only a shortperiod of time is possible without using any solvents, the melt-blendingmethod is economical. Thus, in spite of the requirements of processingat high temperature using equipments such as an extruder, themelt-blending method is more preferred as the method of preparing thepolymer composition of the present invention.

When the melt-blending method with heating is employed, theabove-described components, i.e., polymers (A) and (B) for polymer blend(I), compatibilizers (II) and/or (II'), fillers (III), and otheroptional components, can be kneaded altogether, or these may be kneadedseparately in any arbitrary order.

The filler may be kneaded together with polymers (A) and (B), or may bekneaded before or after polymers (A) and (B) are kneaded. Alternatively,it may be kneaded with a polymer blend composition obtained by firstkneading a mixture of polymers (A) and (B), and compatibilizers (II)and/or (II').

A conventional kneader, mono-axial or bi-axial screw extruder, or thelike, which possesses both heating and mixing functions, can be used asthe equipment for blending these components.

Preferable blending conditions when a kneader is used, for example, area kneader rotation of about 10-200 rpm, preferably about 30-100 rpm, atemperature of about 200°-400° C., preferably 250°-350° C., and ablending time of about 1-60 minutes, preferably 2-10 minutes. No goodblends can be obtained at a rotation less than about 10 rpm or greaterthan about 200 rpm. A blending temperature below 200° C. cannoteffectively melt polymers (A), while a temperature above about 400° C.may cause decomposition of components.

In the case where a biaxial screw extruder, for example, aunidirectional rotation screw extruder with the axial diameter of 40 mmand L/D of 33.5, is used, preferable blending conditions are a screwrotation of about 50-400 rpm, preferably about 100-300 rpm, and atemperature of about 200°-400° C., preferably 250°-350° C. No goodblends can be obtained at a rotation less than about 50 rpm or greaterthan about 400 rpm. A blending temperature below 200° C. cannoteffectively melt polymers (A), while a temperature above about 400° C.may cause decomposition of components.

With a period of time for the blending shorter than about one minute nosufficient blending can be achieved, while that exceeding 60 minutesdoes not bring about the blending effects proportionate to such a longtime.

The polymer composition of the present invention thus obtained bykneading the required components can be molded into a suitable form,such as pellets, films, or the like, depending on the purpose to whichthe composition is directed.

According to the present invention, polymer components (A) and (B) whichare not adequately compatible each other can exhibit excellentcompatibility with the help of the copolymer of maleic anhydride andvinyl type compound (II) or the epoxy-modified styrene-type copolymer(II'), or both of these, used as a compatibilizer. In addition, if afiller is added to the composition, the interface of the filler andpolymers exhibits excellent affinity and binding effects, assuringclosely mixed conditions among these components, thus providing thepolymer blend with superb mechanical properties.

In particular, in the case where the epoxy-modified styrene-typecopolymer (II') is used as the compatibilizer in a very small amount,not only the compatibility among polymers is not reduced at all but alsothere are no problems of unhomogeneity, even when the composition isrepeatedly molded.

Furthermore, the copolymer of maleic anhydride and vinyl type compound(II) and the epoxy-modified styrene-type copolymer (II'), so long asthese are used in amounts within the defined range, do not impair theexcellent heat resistance, moldability, electrical characteristics,mechanical characteristics, and the like inherently possessed by polymercomponents (A) and (B).

The mechanical characteristics and thermal conductivity of the polymerscan be promoted even more by the addition of whisker-type ormono-filament-type inorganic fillers without sacrificing the heatresistance, moldability, and compatibility of the polymers, as well asthe affinity or binding effects between the filler and the polymers.

Because of the excellent electrical characteristics, the polymercomposition of the present invention is suitable as a material forelectrical parts, particularly for molded interconnected devices, usedin high frequency range. According to the test described in detailhereinafter, the polymer composition exhibits a return loss of 30.0 dBor smaller, preferably 25.0 dB or smaller, and more preferably 20.0 dBor smaller, and a insertion loss of 5.0 dB or smaller, preferably 3.0 dBor smaller, and more preferably 1.0 or smaller, in the frequency rangeof 950 MHz to 300 GHz, specifically 3-100 GHz, and more specifically10-30 GHz.

The return loss and insertion loss in the present invention aredetermined by the following test method.

FIG. 1(A) shows a 50 mm×7 mm×1 mm, 50Ω through test leaf used for thedetermination of return loss and insertion loss of the polymercomposition. One side of the 50 mm×7 mm×1 mm test leaf is plated withmetal all over the surface, while on the other side is fixedlongitudinally all through the center of the 50 mm ×7 mm rectangle amicrostrip line, 1.86 mm wide, and 10 μm or thicker, with an impedanceof 50Ω.

The test leaf is enclosed in an electromagnetic shielding holder toexclude outside noise in the determination of return loss and insertionloss.

The return loss and insertion loss of the test leaf can be easilydetermined by measuring the S parameter. Because a signal line of theelectric circuit in the high frequency is the microstrip line with animpedance of 50Ω in this test leaf, the return loss and the insertionloss of the subject material are solely determined using this test leaf.

Usually, copper is plated on the surface. There are no differences inthe results of the return loss and insertion loss measurements, ifnickel or gold is plated instead of the copper. Therefore, plating notonly with copper but also with nickel and gold is acceptable on thesurface of the polymer composition of the present invention. Thus,surface treatments using conventional techniques such as dry plating andwet plating can be implemented over the surface of the polymercomposition of the present invention.

The polymer composition for electrical parts material of the presentinvention is ideal for use in fabricating electronic equipments used inhigh frequency, specifically, materials used for devices, moldedinterconnected devices, or parts, such as printed circuit boardsubstrates, packages, housing, sockets, antennas, coaxial connector,coaxial cables, and waveguides. Owing to the excellent moldability, itcan be molded into electrical parts of any arbitrary shapes by injectionmolding, extrusion, or the like.

Other features of the invention will become apparent in the course ofthe following description of the exemplary embodiments which are givenfor illustration of the invention and are not intended to be limitingthereof.

EXAMPLES Examples 1-17

Polymers and fillers at proportions listed in Tables 1-1 and 1-2 werepreliminary blended in an omnimixer. The blends were continuously meltblended with heating using a biaxial extruder at 300° C. and 200 rpm toobtain polymer compositions.

The following materials and equipment were used in these tests.

Polyether imide

Ultem 1010-1000 (trademark) manufactured by General Electric Co.(U.S.A.).

Polyphenylene ether

Zylone PXL 9102 (trademark) manufactured by Asahi Chemical Industry Co.,Ltd.

Polyester

Rodrun LC-5000 (trademark) manufactured by Unitika, Ltd.

Polycarbonate

NOVAREX 7027A (trademark) manufactured by Mitsubishi ChemicalIndustries, Ltd.

Polyolefin

Syndiotactic polystyrene (M.W. 72,000)

Biaxial extruder

ZE40A (L/D=33.5) (trademark) manufactured by Berstorff A.G. (Germany).

The compositions were molded by injection molding into strips(127×12.7×3 mm), ASTM #1 dumbbells (3 mm), and discs (φ100 ×1.6 mm). Forthe preparation of the strips and ASTM #1 dumbbells, N40-BII (trademark)manufactured by Japan Steel Workers, Ltd. was used at a nozzletemperature of 340° C. The injection machine, Crockner F85 (trademark),manufactured by Crockner Co. was used at a nozzle temperature of 325° C.for the preparation of the discs.

For the evaluation of electrical characteristics (return loss andinsertion loss) at high frequency (100 MHz to 26.5 GHz) the test leavesshown in FIG. 1(A) were prepared by the two-color injection molding atprimary side cylinder temperature of 260° C., a mold temperature of 100°C., and injection pressure of 650 kgf/cm². After the surface treatment,rectangular leaves as shown in FIG. 1(A) were injected at secondary sidecylinder temperature of 370° C., a mold temperature of 95° C., andinjection pressure of 250 kgf/cm². The molded leaves were plated withnon-electrolytic copper to obtain through test leaves with an impedanceof 50Ω.

The following test methods were applied in the determination variouscharacteristics of the polymer compositions.

<Peel Test>

The peel test was performed conforming to ASTM D638 using Instron 4302as the tester at a pulling speed of 5 mm/minute, a bench mark distanceof 115 mm, and at a temperature of 23° C. Five measurements wereaveraged to determine the tensile strength of the samples.

<Bending Test>

The bending test was carried out conforming to ASTM D790 using Instron4302 as the tester at a bending speed of 2 mm/minute, a supporting pointdistance of 50 mm, and at a temperature of 23° C. Five measurements wereaveraged to determine the flexural strength of the samples.

<Izod Impact Test>

The izod impact test was carried out conforming to ASTM D256 using anIzod impact tester manufactured by Toyo Seiki Co., Ltd. at a temperatureof 23° C. <Dielectric constant (ε) and dielectric dissipation factor(tans δ) at 1 MHz and 10 MHz>

These were measured using an impedance/gain-phase analyzer HP-4194A(trademark) and dielectric measurement electrodes HP-16451B (trademark),both manufactured by Hewlett Packard Co., at a temperature of 25° C.

<Heat Distortion Temperature (HDT)>

HDT was measured by a method conforming to ASTM D648 using a heatdistortion tester, S3-MH (trademark), manufactured by Toyo Seiki Co.,Ltd. at a stress of 18.6 kgf/cm². <Electrical Characteristics at HighFrequency>

An equipment, of which the overall construction is shown in FIG. 2, wasused. The return loss and insertion loss were measured by charging highfrequency signals from synthesized sweeper 1 via bridge circuit 4 to DUT3 (the object to be measured) fitted to connector 2, and receiving theresponse by a scalar network analyzer 6 via detector 5. As shown in thecircuit block diagram in FIG. 3, the signals from millimetric wave sweeposcillator 11 enclosed in sweeper 1 are charged to DUT 3 fittedinbetween directional connecters 21 and 22 enclosed in connector 2, viafrequency indicator 12, variable attenuator 13, and isolator 14.

Among response signals from DUT 3, reflected waves are received bynetwork analyzer 5 via directional connecters 21 enclosed in connector2, isolator 23, and detector 41 (which corresponds to detector 4 in FIG.2), and transmitted waves are received by network analyzer 5 viadirectional connecters 22 enclosed in connector 2, isolator 24, anddetector 42 (which corresponds to detector 4 in FIG. 2). In FIG. 3, theDUT 3 terminal opposite to sweeper 1 ends at the resister RT.

FIG. 4 is a portion of the circuit of FIG. 3 and shows a circuit formeasuring reflection coefficient. As shown in this Figure, signals(incident wave) charged to DUT 3 and signals proportionate to responsesignals (reflection wave) are measured, and the reflection coefficientis determined from the ratio of the both measured values.

FIG. 5 is a portion of the circuit of FIG. 3 and shows the circuit formeasuring transmission coefficient. As shown in FIG. 5, signals receivedby network analyzer 5 bypassing DUT 3 (which correspond to incident waveto DUT) and signals proportionate to response signals (transmissionwave) are measured, and the transmission coefficient is determined fromthe ratio of the both measured values.

As the network analyzer, scalar network analyzer HP8757A (trademark)manufactured by Hewlett Packard Co. (U.S.A.); as the synthesizedsweeper, synthesized sweeper HP8341B (trademark) manufactured by HewlettPackard Co. (U.S.A.); as the detector, detector HP11664E (trademark)manufactured by Hewlett Packard Co. (U.S.A.); and as the connecter,Whiltron connecter K (trademark) manufactured by Anritsu Co., Ltd., wererespectively used.

The determination at 100 GHz was carried out on a test leaf with a sizeof 220×200×1 and the maximum surface roughness (R_(max)) of 0.05 μmusing a semi-confocal type open resonator consisting of a sphericalmirror and a plane mirror to which the test leaf is attached.

The results are shown in Tables 2-1 and 2-2.

The following standards were applied to the evaluation of variouscharacteristics of the polymer compositions.

<Heat Resistance>

    ______________________________________                                        Heat distortion                                                               temperature under load                                                                             Heat resistance                                          ______________________________________                                        190° C. and higher                                                                          Good (AAA)                                               180°-190° C.                                                                         Fair (BBB)                                               180° C. and lower                                                                           Bad (CCC)                                                ______________________________________                                    

<Platability>

The polymer composition was plated with copper and the plating closenesswas evaluated by pressing an adhesion tape (12 mm wide cellophaneadhesion tape defined in JIS Z 1522) with finger for about 10 secondsover the length of 50 mm or longer so as to leave no air bubbles in theinterface, following which the tape was pulled vertically away from theplated surface to peel it off to examine if the plate membrane wasraised or the plated metal was attached to the tape. Samples withneither raised plate membrane nor attachment to the plated metal to thetape were rated as good (AAA); those with partly raised plate membrane,as fair (BBB); and those with peeled plate membrane, as bad (CCC).

<Moldability (Melt-Flowability)>

The melt-flow length was taken as the standard of the moldability. Thepolymer composition was melted and injected using an injection mold at acylinder temperature of 340° C. and a mold temperature of 150° C., andthe length for which the melted polymer composition flowed was measured.An open mold die with a spool having a diameter of 1.5 mm and a 0.4mm×2.0 mm side gate was used for the measurement. Samples with themelt-flow length longer than 25 mm were rated as good (AAA); those withthe melt-flow length of 20-25 mm, as fair (BBB); and those with themelt-flow length shorter than 20 mm, as bad (CCC).

<Recycle Moldability>

External appearance of (a) molded articles prepared simply kneading thepolymer composition and (b) those prepared from these molded articles(a) by melting and remolding them was compared. Sample polymercompositions producing molded articles (b) having an external appearanceequivalent to molded articles (a) were rated as good (AAA); thoseproducing (b) having an external appearance slightly worse than (a), asfair (BBB); and those producing (b) having an external appearance worsethan (a), as bad (CCC).

<Electrical Characteristics>

Electrical characteristics of the compositions were evaluated accordingto the following standard.

    ______________________________________                                        Return loss   Insertion loss Evaluation                                       ______________________________________                                        Less than 25.0 dB                                                                           Less than 3.0 dB                                                                             Good (AAA)                                       25.0 to 30.0 dB                                                                             3.0 to 5.0 dB  Fair (BBB)                                       Greater than 30.0 dB                                                                        Greater than 5.0 dB                                                                          Bad (CCC)                                        ______________________________________                                    

                  TABLE 1-1                                                       ______________________________________                                                     Example                                                                       1   2     3     4   5   6   7   8   9                            ______________________________________                                        <Polymer                                                                      component (I)>                                                                Polyether imide (PEI)                                                                        50    50    50  50  50  70  30  50  50                         Polyester (LCP)                                                               Polyphenylene ether                                                                          50    50    50  50  50  30  70  50  50                         (PPE)                                                                         Polycarbonate (PC)                                                            Polyolefin                                                                    <Compatibilizer (II) or                                                       (II')>                                                                        Maleic anhydride-styrene                                                                     5               5   5   5   5   5   5                          copolymer (St-MAnh)                                                           Epoxy-modified styrene-                                                                            0.5   0.5                                                styrene copolymer                                                             (EpSt-St)                                                                     Epoxy-modified styrene-                                                       methyl-methacrylate                                                           copolymer (EpSt-MMA)                                                          <Inorganic filler (III)>                                                      Potassium titanate whisker 30  30                                             Aluminum borate whisker            30  30  30  40  20                         ______________________________________                                    

                  TABLE 1-2                                                       ______________________________________                                                     Example                                                                       10  11    12    13  14  15  16   17                              ______________________________________                                        <Polymer                                                                      component (I)>                                                                Polyether imide (PEI)                                                                        50    50                50  42.5 42.5                          Polyester (LCP)            50  70  50      15   15                            Polyphenylene ether        50  30  50      42.5 42.5                          (PPE)                                                                         Polycarbonate (PC)                                                                           50    50                                                       Polyolefin                             50                                     <Compatibilizer (II) or                                                       (II')>                                                                        Maleic anhydride-styrene   5   5   5   5   5    5                             copolymer (St-MAnh)                                                           Epoxy-modified styrene-                                                       styrene copolymer                                                             (EpSt-St)                                                                     Epoxy-modified styrene-                                                                      5     5                                                        methyl-methacrylate                                                           copolymer (EpSt-MMA)                                                          <Inorganic filler (III)>                                                      Potassium titanate whisker                                                                         30                                                       Aluminum borate whisker            20  30       30                            ______________________________________                                    

                                      TABLE 2-1                                   __________________________________________________________________________                               Example                                                                       1   2   3   4   5   6   7   8   9                  __________________________________________________________________________    Tensile strength                                                                              kgf/cm.sup.2                                                                             860 880 1150                                                                              1120                                                                              1180                                                                              1280                                                                              950 1250                                                                              1080               Tensile modulus kgf/cm.sup.2                                                                             24000                                                                             25000                                                                             127000                                                                            130000                                                                            123000                                                                            135000                                                                            98000                                                                             129000                                                                            112000             Flexural strength                                                                             kgf/cm.sup.2                                                                             1250                                                                              1320                                                                              1400                                                                              1350                                                                              1320                                                                              1350                                                                              1050                                                                              1340                                                                              1110               Flexural modulus                                                                              kgf/cm.sup.2                                                                             27000                                                                             27000                                                                             100000                                                                            99000                                                                             105000                                                                            125000                                                                            87000                                                                             143000                                                                            102000             Izod impact strength, notched                                                                 kgf/cm.sup.2                                                                             5.0 4.0 2.1 1.9 2.8 2.9 2.8 2.0 3.1                Dielectric constant (ε)                                                               (1 MHz, 25° C.)                                                                   2.81                                                                              2.80                                                                              3.05                                                                              3.15                                                                              2.95                                                                              2.97                                                                              2.86                                                                              2.99                                                                              2.88                               (10 MHz, 25° C.)                                                                  2.75                                                                              2.73                                                                              3.00                                                                              3.12                                                                              2.82                                                                              2.90                                                                              2.80                                                                              2.91                                                                              2.84               Dielectric dissipation                                                                        (1 MHz, 25° C.)                                                                   0.0023                                                                            0.0025                                                                            0.0045                                                                            0.0051                                                                            0.0029                                                                            0.0039                                                                            0.0025                                                                            0.0032                                                                            0.0027             factor (tan δ)                                                                          (10 MHz, 25° C.)                                                                  0.0035                                                                            0.0035                                                                            0.0059                                                                            0.0059                                                                            0.0033                                                                            0.0035                                                                            0.0030                                                                            0.0033                                                                            0.0031             Return loss/-dB (18 GHz, 25° C.)                                                                  16  16.5                                                                              20.3                                                                              21.0                                                                              19.5                                                                              19.9                                                                              19.0                                                                              21.5                                                                              19.1                               (26 GHz, 25° C.)                                                                  26.1                                                                              26.7                                                                              13.3                                                                              13.4                                                                              13.0                                                                              15.0                                                                              13.0                                                                              15.5                                                                              12.5                               (100 GHz, 25° C.)                                                                 21                                                 Insertion loss/-dB                                                                            (18 GHz, 25° C.)                                                                  3.0 3.2 1.7 1.8 1.9 2.5 1.8 2.3 1.9                                (26 GHz, 25° C.)                                                                  4.5 4.9 2.9 2.9 2.7 2.6 2.5 3.0 2.6                                (100 GHz, 25° C.)                                                                 2.3                                                Heat distortion °C., @ 18.6 kgf/cm.sup.2                                                          176 180 186 183 191 202 180 198 181                temperature                                                                   Coefficient of thermal                                                                        cal/cm · sec · °C.                                              5.0 5.0 9.0 8.7 8.9 8.4 8.0 9.8 6.9                conductivity    (× 10.sup.-4)                                           Coefficient of linear                                                                         ppm/°C.                                                                           57  56  28  26  24  29  22  18  29                 thermal expansion                                                             __________________________________________________________________________

                                      TABLE 2-2                                   __________________________________________________________________________                             Example                                                                       10  11  12  13  14  15  16  17                       __________________________________________________________________________    Tensile strength                                                                             kgf/cm.sup.2                                                                            850 1050                                                                              960 1050                                                                              1190                                                                              1290                                                                              960 1290                     Tensile modulus                                                                              kgf/cm.sup.2                                                                            28000                                                                             85000                                                                             35000                                                                             42000                                                                             145000                                                                            138000                                                                            33000                                                                             142000                   Flexural strength                                                                            kgf/cm.sup.2                                                                            1280                                                                              1340                                                                              1380                                                                              1380                                                                              1450                                                                              1390                                                                              1300                                                                              1400                     Flexural modulus                                                                             kgf/cm.sup.2                                                                            28000                                                                             91000                                                                             39000                                                                             44000                                                                             162000                                                                            148000                                                                            38000                                                                             150000                   Izod impact strength, notched                                                                kgf/cm.sup.2                                                                            4.5 3.0 2.9 2.9 2.2 2.0 4.8 2.5                      Dielectric constant (ε)                                                              (1 MHz, 25° C.)                                                                  2.80                                                                              2.98                                                                              3.01                                                                              3.10                                                                              3.05                                                                              2.90                                                                              2.85                                                                              2.87                                    (10 MHz, 25° C.)                                                                 2.75                                                                              2.88                                                                              2.90                                                                              2.93                                                                              2.85                                                                              2.84                                                                              2.83                                                                              2.85                     Dielectric dissipation                                                                       (1 MHz, 25° C.)                                                                  0.0038                                                                            0.0040                                                                            0.0041                                                                            0.0050                                                                            0.0043                                                                            0.0030                                                                            0.0025                                                                            0.0029                   factor (tan δ)                                                                         (10 MHz, 25° C.)                                                                 0.0039                                                                            0.0039                                                                            0.0047                                                                            0.0055                                                                            0.0045                                                                            0.0020                                                                            0.0031                                                                            0.0035                   Return loss/-dB                                                                              (18 GHz, 25° C.)                                                                 16.9                                                                              21.3                                                                              19.5                                                                              23.5                                                                              21.0                                                                              21.5                                                                              18.8                                                                              19.5                                    (26 GHz, 25° C.)                                                                 28.1                                                                              15.2                                                                              18.8                                                                              20.0                                                                              20.1                                                                              20.8                                                                              19.5                                                                              20.1                     Insertion loss/-dB                                                                           (18 GHz, 25° C.)                                                                 3.5 2.0 2.6 3.0 2.8 3.5 2.4 2.6                                     (26 GHz, 25° C.)                                                                 4.9 3.2 2.7 3.1 2.9 3.6 2.5 2.9                      Heat distortion                                                                              °C., @ 18.6 kgf/cm.sup.2                                                         167 175 191 205 208 192 190 202                      temperature                                                                   Coefficient of thermal                                                                       cal/cm · sec · °C.                                             4.9 8.2 5.1 5.2 6.9 8.2 5.3 8.8                      conductivity   (× 10.sup.-4)                                            Coefficient of linear                                                                        ppm/°C.                                                                          52  28  58  57  29  22  56  23                       thermal expansion                                                             __________________________________________________________________________

Comparative Example 1-7

Polymer compositions were prepared in the same manner as in Examples1-17 from polymers and fillers at proportions listed in Table 3.

Various characteristics of these compositions were measured andevaluated in the same manner as in Examples 1-17. The results are shownin Tables 4 and 5.

                  TABLE 3                                                         ______________________________________                                                     Comparative Example                                                           1    2      3      4    5   6   7                                ______________________________________                                        <Polymer                                                                      component (I)>                                                                Polyether imide (PEI)                                                                        100                     50  50  50                             Polyester (LCP)       100              50                                     Polyphenylene ether               100      50  50                             (PPE)                                                                         Teflon                       100                                              <Compatibilizer (II) or                                                       (II')>                                                                        Maleic anhydride-styrene                                                      copolymer (St-MAnh)                                                           Epoxy-modified styrene-                    10  5                              styrene copolymer                                                             (EpSt-St)                                                                     Epoxy-modified styrene-                                                       MMA copolymer                                                                 (EpSt-MMA)                                                                    <Inorganic filler (III)>                                                      Potassium titanate whisker                                                    Aluminum borate whisker                                                       ______________________________________                                    

                                      TABLE 4                                     __________________________________________________________________________                             Comparative Example                                                           1   2   3   4   5   6   7                            __________________________________________________________________________    Tensile strength                                                                             kgf/cm.sup.2                                                                            1100                                                                              1800                                                                              400 690 2000                                                                              850 865                          Tensile modulus                                                                              kgf/cm.sup.2                                                                            19000                                                                             --  --  12000                                                                             25000                                                                             21000                                                                             21000                        Flexural strength                                                                            kgf/cm.sup.2                                                                            1400                                                                              1400                                                                              --  1030                                                                              1490                                                                              1200                                                                              1240                         Flexural modulus                                                                             kgf/cm.sup.2                                                                            30000                                                                             100000                                                                            3500                                                                              23000                                                                             32000                                                                             24000                                                                             24000                        Izod impact strength, notched                                                                kgf/cm.sup.2                                                                            2.5 23  16  6.9 2.3 4.5 4.2                          Dielectric constant (ε)                                                              (1 MHz, 25° C.)                                                                  3.25                                                                              3.40                                                                              2.10                                                                              2.57                                                                              3.51                                                                              2.77                                                                              2.79                                        (10 MHz, 25° C.)                                                                 3.18                                                                              3.40                                                                              2.10                                                                              2.51                                                                              3.40                                                                              2.75                                                                              2.79                         Dielectric dissipation                                                                       (1 MHz, 25° C.)                                                                  0.0051                                                                            0.040                                                                             0.0001                                                                            0.0003                                                                            0.008                                                                             0.0020                                                                            0.0023                       factor (tan δ)                                                                         (10 MHz, 25° C.)                                                                 0.0065                                                                            0.041                                                                             0.0002                                                                            0.0005                                                                            0.009                                                                             0.0030                                                                            0.0030                       Return loss/-dB                                                                              (18 GHz, 25° C.)                                                                 30.5                                                                              35.0                                                                              24.8                                                                              25.5                                                                              32.5                                                                              17.8                                                                              17.9                                        (26 GHz, 25° C.)                                                                 31.3                                                                              38.2                                                                              20.4                                                                              22.0                                                                              33.0                                                                              25.0                                                                              27.2                         Insertion loss/-dB                                                                           (18 GHz, 25° C.)                                                                 7.8 8.5 0.99                                                                              30  8.2 3.3 3.9                                         (26 GHz, 25° C.)                                                                 7.9 8.8 1.6 3.8 8.5 3.9 4.0                          Heat distortion                                                                              °C., @ 18.6 kgf/cm.sup.2                                                         190 170 51  153 190 171 173                          temperature                                                                   Coefficient of thermal                                                                       cal/cm · sec · °C.                                             4.9 5.3 4.2 4.9 5.0 5.0 5.1                          conductivity   (× 10.sup.-4)                                            Coefficient of linear                                                                        ppm/°C.                                                                          54  56  79  57  54  51  57                           thermal expansion                                                             __________________________________________________________________________

                  TABLE 5                                                         ______________________________________                                                      Metal           Recycle                                                                              Electrical                                      Heat   Plat-   Mold-   Mold-  character-                                      resistance                                                                           ability ability ability                                                                              istics                                   ______________________________________                                        Example                                                                       1        BBB      AAA     AAA   AAA    BBB                                    2        BBB      AAA     AAA   AAA    BBB                                    3        AAA      AAA     BBB   BBB    AAA                                    4        AAA      AAA     BBB   BBB    AAA                                    5        AAA      AAA     BBB   AAA    AAA                                    6        AAA      AAA     BBB   AAA    AAA                                    7        AAA      BBB     BBB   AAA    AAA                                    8        AAA      BBB     BBB   BBB    AAA                                    9        AAA      AAA     BBB   AAA    AAA                                    10       BBB      AAA     AAA   AAA    BBB                                    11       AAA      AAA     BBB   AAA    AAA                                    12       AAA      AAA     AAA   AAA    AAA                                    13       AAA      AAA     AAA   AAA    AAA                                    14       AAA      AAA     AAA   AAA    AAA                                    15       AAA      AAA     BBB   BBB    AAA                                    16       AAA      AAA     AAA   AAA    AAA                                    17       AAA      AAA     BBB   AAA    AAA                                    Comparative                                                                   Example                                                                       1        AAA      CCC     AAA   AAA    CCC                                    2        BBB      CCC     AAA   AAA    CCC                                    3        CCC      CCC     CCC   CCC    AAA                                    4        CCC      CCC     AAA   AAA    BBB                                    5        AAA      BBB     AAA   CCC    CCC                                    6        BBB      BBB     AAA   CCC    BBB                                    7        BBB      AAA     AAA   CCC    BBB                                    ______________________________________                                    

All polymer compositions in the Examples exhibited remarkable lowerreturn loss (less than 30 dB) and lower insertion loss (less than 5 dB)than polymer compositions in Comparative Examples, demonstrating theirsuperior electrical characteristics. This applies to polymercompositions to which potassium titanate whisker or aluminum boratewhisker was added as organic fillers (Examples 3-9, 11, 14, 15 and 17).

As can be seen in Comparative Examples 1 and 2, polyether imide andliquid crystalline polyester, which are known as engineering plasticspossessing superior heat resistance, exhibited comparatively highdielectric constant. Their return loss and insertion loss at highfrequency were also comparatively large. Teflon, which is arepresentative low dielectric constant polymer, exhibited unduly poormoldability and platability, even though its electrical characteristicsare excellent (Comparative Example 3).

The polymer composition of Comparative Example 4 is insufficient in theheat resistance, although the moldability, electrical characteristics,and platability are acceptable.

The polymer composition of Comparative Example 5 is inferior in theelectrical characteristics, although it is excellent in the heatresistance and mechanical characteristics.

The polymer compositions of Comparative Examples 6 and 7 have poorrecycle moldability, even though they are excellent in the platability,heat resistance and electrical characteristics.

Based on the above results, the polymer composition of the presentinvention was proven to have excellent heat resistance, platability andmoldability, and at the same time, to exhibit low dielectric constantand dielectric dissipation factor, showing small reflection andinsertion losses at high frequency.

As illustrated above, the polymer composition for electrical material ofthe present invention exhibits only a small return loss of electricsignals (less than 30 dB) and a small insertion loss of electric signals(less than 5.0 dB) over a wide high-frequency range (950 MHz to 300GHz). This ensures selection of wiring circuit board substrates from awide variety of materials. In addition, because the polymer compositionof the present invention have excellent moldability, not only variouscircuit designs and package designs are possible using this polymercomposition, but also the composition can be easily molded into avariety of parts devices, and molded interconnected devices, such aspackages, connectors, printed circuit substrates, sockets, coaxialconnectors, coaxial cables, and various housings.

Moreover, since the addition of fillers to the composition does notreduce these excellent characteristics, electrical parts with superbmechanical characteristics can be obtained.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

What is claimed is:
 1. A polymer composition for electrical partmaterial which comprises,(I) a polymer blend which comprises,(A) (a) apolyether imide represented by the following formula (1), ##STR33##wherein n indicates an integer of 1-10,000, R₁ represents a group##STR34## and R₂ represents a group ##STR35## and optionally (b)polyesters represented by the following formulas (2-1) to (2-11),##STR36## wherein n indicates an integer of 1-10,000, ##STR37## whereinn indicates an integer of 1-10,000, ##STR38## wherein n indicates aninteger of 1-10,000, ##STR39## wherein n indicates an integer of1-10,000, ##STR40## wherein n indicates an integer of 1-10,000,##STR41## wherein n indicates an integer of 1-10,000, ##STR42## whereinx and y are integers satisfying an equation x+y=2 to 10,000, ##STR43##wherein x and y are integers satisfying an equation x+y=2 to 10,000,##STR44## wherein x and y are integers satisfying an equation x+y=2 to10,000, ##STR45## wherein n indicates an integer of 1-10,000, or##STR46## wherein x and y are integers satisfying an equation x+y=2 to10,000, and (B) at least one polymer selected from the group consistingof, (c) polyphenylene ethers represented by the following formula (3),##STR47## wherein n indicates an integer of 1-1000, Y₁, Y₂, Y₃, and Y₄individually represented hydrogen or methyl group, (d) polyolefinsrepresented by the following formula (4), ##STR48## wherein R is analkyl group having 1-10 carbon atoms, an aromatic group having 6-10carbon atoms, or a hydrogen, an n is an integer of 1-100,000, and (e)polycarbonates represented by the following formulas (5-1) to (5-7),##STR49## wherein n indicates an integer of 1-10,000, ##STR50## whereinn indicates an integer of 1-10,000, ##STR51## wherein n indicates aninteger of 1-10,000, ##STR52## wherein n indicates an integer of1-10,000, ##STR53## wherein n indicates an integer of 1-10,000,##STR54## wherein n indicates an integer of 1-10,000, or ##STR55##wherein n indicates an integer of 1-10,000; and (II') an epoxy-modifiedstyrene copolymer, wherein the amount of component (II') is 0.1 to 1.0part by weight for 100 parts by weight of the total amount of saidpolymer blend (I).
 2. The polymer composition for electrical partmaterial according to claim 1, wherein said epoxy-modified styrenecopolymer (II') is a graft copolymer.
 3. The polymer composition forelectrical part material according to claim 1, wherein saidepoxy-modified styrene copolymer (II') is at least one copolymerselected from the group consisting of epoxy-modified styrene-styrenecopolymers and epoxy-modified styrene-methyl methacrylate copolymers. 4.The polymer composition for electrical part material according to claim1, further comprising a filler.
 5. The polymer composition forelectrical part material according to claim 4, wherein said filler is atleast one filler selected from the group consisting of glass, aluminumoxide, magnesium oxide, beryllium oxide, titanium oxide, aluminumnitride, silicon nitride, boron nitride, titanium nitride, siliconcarbide, potassium titanate, aluminum borate, and calcium carbonate. 6.The polymer composition for electrical part material according to claim4, wherein said filler is a whisker filler or a monofilament filler. 7.The polymer composition for electrical part material according to claim1, having a return loss of 30.0 dB or smaller and an insertion loss of5.0 dB or smaller in the frequency range of 950 MHz to 300 GHz, whenmeasured on a 50 mm×7 mm rectangular test leaf, with a thickness of 1mm, of which the one side is plated all over the surface and the otherside has a microstrip line with an impedance of 50Ω, 1.86 mm wide and atleast 10 μm thick, affixed longitudinally all through the center of the50 mm×7 rectangle.
 8. A polymer composition for electrical part materialwhich comprises,(I) a polymer blend which comprises,(A) (a) a polyetherimide represented by the following formula (1), ##STR56## wherein nindicates an integer of 1-10,000, R₁ represents a group ##STR57## and R₂represents a group ##STR58## and optionally (b) polyesters representedby the following formulas (2-1) to (2-11), ##STR59## wherein n indicatesan integer of 1-10,000, ##STR60## wherein n indicates an integer of1-10,000, ##STR61## wherein n indicates an integer of 1-10000, ##STR62##wherein n indicates an integer of 1-10,000, ##STR63## wherein nindicates an integer of 1-10,000, ##STR64## wherein n indicates aninteger of 1-10,000, ##STR65## wherein x and y are integers satisfyingan equation x+y=2 to 10,000, ##STR66## wherein x and y are integerssatisfying an equation x+y=2 to 10,000, ##STR67## wherein x and y areintegers satisfying an equation x+y=2 to 10,000, ##STR68## wherein nindicates an integer of 1-10,000, or ##STR69## wherein x and y areintegers satisfying an equation x+y=2 to 10,000, (B) at least onepolymer selected from the group consisting of, (c) polyphenylene ethersrepresented by the following formula (3), ##STR70## wherein n indicatesan integer of 1-1000, Y₁, Y₂, Y₃, and Y₄ individually represent hydrogenor methyl group, (d) polyolefins represented by the following formula(4), ##STR71## wherein R is an alkyl group having 1-10 carbon atoms, anaromatic group having 6-10 carbon atoms, or a hydrogen, an n is aninteger of 1-100,000, and (e) polycarbonates represented by thefollowing formulas (5-1) to (5-7), ##STR72## wherein n indicates aninteger of 1-10,000, ##STR73## wherein n indicates an integer of1-10,000, ##STR74## wherein n indicates an integer of 1-10,000,##STR75## wherein n indicates an integer of 1-10,000, ##STR76## whereinn indicates an integer of 1-10,000, ##STR77## wherein n indicates aninteger of 1-10,000, or ##STR78## wherein n indicates an integer of1-10,000; and (II) a copolymer of maleic anhydride and a vinyl compoundand (II') an epoxy-modified styrene copolymer,wherein the amount ofcomponents (II) and (II') is 0.1 to 50 parts by weight for 100 parts byweight of the total amount of said polymer blend (I).
 9. The polymercomposition for electrical part material according to claim 8, whereinthe amount of said component (II') is 0.1 to 1.0 part by weight for 100parts by weight of the total amount of said polymer blend (I).